Printed circuit type fuse



June 14, 1960 s ETAL 2,941,059

PRINTED CIRCUIT TYPE FUSE Filed Sept. 16, 1957 INVENTORS ROB/5R T bf5/M6 BY Hs aszer/P. L/LLEY A TTORNEY United States Patent PRINTEDCIRCUIT TYPE FUSE Robert H. Sims, Oak Park, and Herbert R. Lilley,Pontiac,

Micln, assignors to General Motors Corporation, Detroit, Mich., acorporation of Delaware Filed Sept. 16, 1957, Ser. No. 684,032

4 Claims. (31. 200-129 This invention relates generally to printedcircuit type electric components, and particularly, to printed circuittype fusible protective devices or fuses" operative to inter rupt anelectric circuit on occurrence of overload currents or short circuitcurrents.

An object of this invention is to provide a new type of fusibleprotective device for use in electric circuits.

Another object is to provide a fusible protective device having a rigidinsulating base with one side covered with electrical conductingmaterial in a manner to provide a current conducting bridge which isinterrupted by excessive heating due to electric current in excess ofthe current capacity of the bridge of conducting material.

Another object is to provide a fusible protective device of printedcircuit type construction including a fuse material bonded to aninsulator board for use in an electric circuit.

Another object is to provide a fuse and fuse block assembly including amolded fuse block of insulating material having openings for insertionof electric terminals connectible in an electric circuit together with afuse material bonded on an insulator board as a printed circuit typefuse engageable between the terminals as a circuit protecting device.

Another object is to provide a fuse and fuse block assembly including aninsulating housing for connection with electrical terminals in anelectric circuit to include a printed circuit type. fuse of conductingmaterial on an insulating board inserted between the terminals.

Another object is to provide a fusible protective device including aU-shaped insulator board with leg portions inter-connected by a bridgeadapted both as a handle for manually inserting and removing theprotective device relative to the terminals in an electrical circuit andas -a base for electrical conducting fuse material secured as a printedcircuit to each leg portion and across the bridge of the insulatorboard.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the invention is clearlyshown.

In the drawings:

Figure 1 is a plan view'of a fusible protective device in accordancewith the present invention.

Figure 2 is a side elevational view of the device in Figure 1.

Figure 3 is a perspective view of a fuse and fuse block assembly inaccordance with-the present invention.

'Figure 4 is an exploded perspective view of a modified printed circuittype fuse and fuse block in accordance with the present invention.

In Figure 1 there is a printed circuit type electric component includingan insulator board generally designated by numeral of an insulatingmaterial such as a fiber, synthetic resin, or plastic capable ofwithstanding heat to an extent necessary in accordance with the presentinvention. Plastic or resinous sheet material either with ice or withoutfillers, such as fabric, mica, woven glass cloth, etc., may be used.Either cold setting or heat setting resins may be used such asphenol-formaldehyde, phenolfurfurol, furan, urea-formaldehyde, melamine,methyl turing a printed circuit type electrical component including theunderlying insulating material upon which conducting material isprinted. A suitable relationship is established between the insulatorboard and the conducting material such that moist and humid climaticconditions will not have deteriorating effects on the printed circuittype fusible protective device of the present invention.

The insulator board 10 shown in Fig. 1 is a substantially U-shaped rigidinsulating base including leg portions 12 and 14 joined to each other byan intermediate portion or bridge 16. In the embodiment of the inventionillustrated in Fig. 1, the bridge 16 includes a lower surface area 18 onwhich fusible electrical conducting material is provided and an uppersurface 19 providing a panel portion for manually inserting and removingthe insulating base 10 from electrical terminals engaging the printedcircuit material as will be described in further detail below. Thehandle portion 19 can be formed extending upwardly from the lowersurface 18 of the bridge 16 such that a wing-like structure which can begrasped by fingers or a suitable tool, such as pliers, for inserting andremoving the fusible protective device 10 in an electric circuit. Alsoas an aid for inserting and removing the printed circuit type fuse withthe wing-like structure, an aperture or recess 21 is provided in thehandle portion 19 such that finger tips can securely engage oppos'itesurfaces of the insulating board 10 in the upper portion 19. It is alsopossible that a hooked rod may be inserted through the hole 21 forpulling the device 10 out of an electric circuit as in the presentinvention.

A fusible electrical conducting material, generally indicated by numeral20, is shown provided on the insulator board 10 in Fig. 1. Thisconducting material 20 can be applied in any manner such as by a dippingoperation, a coating method, a bonding of electric conducting materialto the insulator board or by wedging of the elec tric conductingmaterial into a notched recess that may be provided in bridge portion 18and around the corners of the leg portions 12 and 14', respectively. Inany,

event the method of securing the electrical conducting material to theinsulating board can be any of various known methods familiar to thoseskilled in the art of printed circuits whereby a proper printed circuitrelationship is established between the conducting material 20 and theinsulator board 10.

Fig. 1 further illustrates phantom representations of female electricalterminals 22 and 24. Shown with each of the terminals is a conductor 25fastened by crimping lateral tangs 26 thereof onto a wire 27 covered byan insulating material 28 which is also secured by crimped tabs 29 tothe conductor receiving portion 30. Each terminal is further providedwth a flattened fioor portion, 32 and 34, engageable with the legportions 12 and 14, respectively, of the insulator board 10. Each floorportion is provided with laterally bent over side wing portions 32' and34 which are curved around the edges 12' and 14 of the leg portions tobe in sliding engagement with the electrical conducting material 20provided on each of the legs 12 and 14 of the insulator board 10. Anelectrical contact is established through engagement of the bent overside wing portions 32 and 34 of the terminals against the electricalconducting material 20.

As shown in Fig. 1, the electrical conducting mateial 20 on the legportions 12 and 14 covers the entire surface area of the leg portionswith metallic material represented by numerals 42 and 44, respectively.The leg portion 12 and 14 are reduced in size laterally to provideshoulders 42 and 44 respectively on each of opposite sides of theinsulator'board 10. The shoulders 42 and 44 serve as stops to preventexcess movement of the insulator board 10 relative to the terminals 22and 24 when legs 12 and 14 are inserted and engaged onto the floorportions 32 and 34 relative to the bent over side wing portions 32' and34. and 44 are adapted as stop members to engage against ends of thebent over side wing portions 32' and 34'.

As mentioned earlier, the electrical conducting material 24) can besecured to the insulator board 10 in any suitable manner. Fig. 2illustrates a side view of the insulator board 10 covered withelectrical conducting material 21 as described with Fig.1. The shoulder42' is visible in Fig. 2 and a bevelled r tapered end portion generallyindicated by numeral 46 is shown as provided on each of the leg portions12 and 14 of the insulator board. Only the leg portion 12 is visible inFig. 2, but it is to be understood that a bevelled portion 46 is provided on leg portion 14 just as is provided for leg portion 12. Thisbevelled portion facilitates insertion of the leg portions into theterminals 22 and 24 described with Fig. 1. Further, the bevelled portion46 assures that the bent over side wing portions 32' and 34 of theterminals are permitted to slide positively over the surfaces 42 and 44of the printed circuit conducting material on the legs 12 and 14,respectively, prior to positive electrical engagement relative to theconducting material. After passing over the bevelled portion 46, theside wing portions are in sliding engagement with the electricalconducting material and a back surface 48 of the insulator board. Due tothe guiding action of the bevelled portion 46, the side wing portions ofthe terminals will not damage ortear away the end tab areas 42" and 44"of the conducting material 42 and 44 on the leg portions 12 and 14,respectively, of the insulator board 10. As is apparent in Fig. 2, theconducting material 20 has been bonded -or coated to the insulator boardon surface outlined with Fig. 1 on one side of the insulator board.

It is to be understood that the electrical conducting material as bondedor secured to the insulating board 10 is such that heating of theconducting material caused by electric current carried by a bridgeportion 50 of the electrical conducting material secured to the bridgesurface 18 as shown in Fig. 1 will determine the fuse rating of thedevice in the present invention. In adidtion to being affected by theelectrical resistance of the type of metal or alloy material used informing the conducting material 2!), the fuse rating is dependent uponand is variable in accordance with the shape and thickness of materialprovided in the bridge 5110f conducting material. The current rating canbe appreciably altered by providing wider and thicker portions ofconducting material in the bridge 50. In keeping with the presentinvention, varying fuse ratings, such 6, 12, 14, 15, 20, 25, etc.,amperes, can be provided with the device of the present invention.However, it is necessary that the insulator board 10 be formed of aninsulating material capable of withstanding the heating of currentcarried by the conducting material bridge 50 in a continuous electriccircuit up to and including the fuse rating of the particular printedcircuit type fuse provided in accordance with the present invention. Forpurposes of illustration, the printed circuit type fuse illustrated inFigs. 1 and 2 may be used in an electrical circuit of an automobile (notshown) in which a fuse block is provided at a convenient location suchas on a fire wall or behind a dashboard (not shown) of a vehicle.

, A molded plastic fuse block 60 is shown in a perspective view of Fig.3. This fuse block 60 can be suitably at- Thus the shoulders 42'.

4 tached to a fire wall or dashboard of an automobile by means of a boltor screw (not shown) which may be inserted through a hole 62 provided ina lateral flange 64 for mounting purposes with the fuse block 60. Fig. 3illustrates the substantially U-shaped printed circuit type electriccomponent 10 of the present invention inserted with legs 12 and 14 (notvisible in Fig. 3) extending into openings 72 and-74, respectively, asprovided with the fuse block 60. A plurality of these openings 72 and 74spaced longitudinally and laterally relative to each other can beprovided on each of opposite sides of the fuse block 60 so that a bankor plurality of printed circuit type electric components 10'can bemounted in a row with the fuse block to serve multiple circuitsconnected through conduits 25 which are attached to the terminals 22 and24 described with Fig. 1. A pair of terminals 22 and 24 are shown inFig. 3 for insertion in the foremost openings 72 and 74 of the block 60shown in the view of Fig. 3. The openings 72 and 74 may extendtransversely through the body of the fuse block 60 permitting theterminals 22 and 24 to be inserted from the bottom of the fuse blockwhile the printed circuit type fuses of the present invention can beinserted from the top 66 of the fuse block. If necessary, a cover, notshown, of insulating material can be secured to the bottom of the fuseblock to insulate and close off the bottom of the openings of 72 and 74into which the terminals 22 and 24 are inserted.

It is apparent that the U-shaped printed circuit ty'pe electric fusesillustrated in Figs. 1, 2, and 3 when mounted as shown in Fig. 3 provideelectrical connection between terminals 22 and 24 in staggeredrelationship longitudinally and laterally relative to the plurality ofopenings 72 and 74 provided with the insulating fuse block 60.Furtheremore, the handle portion 19 of the insulator board 10 extendsupwardly from the conducting material 20 a suflicient amount such thatthe conducting material 201s spaced well below edge portion 19 of eachhandle por tion 19. Thus, the conducting material 20 forming the. bridge50 of electrical conducting material on thebridge' surface 18 is spacedwell away from the edges 19' and is remote from any shorting connectionwith other wiring or metal which may be adjacent to the fire wall ordashboard of the motor vehicle (not shown).

Figure 3 illustrates a slightly modified version ofthe;

printed circuit type fuse of Fig. 1 in that an additional bridge 50 ofconducting material is shown secured to the' insulator board 10. Thebridges of conducting material 50 and 50 illustrated in Fig. 3 arespaced parallelto' present invention. However, the parallel bridges 50and 50 can also be provided with the smaller ampere fuse.

ratings for facilitating heat dissipation so long as the shape andthickness of the bridges are in accordance with the particular fuserating'requirements.

The holes 21provided in each wing-like handle portion 19 of theinsulator board 10 are clearly visible in the perspective view of Fig.3. With the close spaced rela.''.

tionship of the printed circuit type fuses in a row or bank using fuseblock 60 as shown in Fig. 3, it is often'difficultfor finger tips to beinserted between alternate printed circuit type fuses to remove a burnedout fuse. There-l fore, it may be advisable to remove a burned outprinted" circuit type fuse from block 60 with a tool such-as may beformed by a wire having a hooked end to be inserted":

into the holes 21 for removal of a fuse. Fig. 3 also illustratesshoulder portions 42 and 44 in engagement with. the top surface of thefuse blOCk'60i as steps or abutments also engagable with wing portionsof the terminals 22 and 24 as mentioned earlier.

Figure 4 illustrates another embodiment of a printed circuit type fuseand fuse block assembly in accordance with the present invention.Electrical terminals of a straight typesuch as terminal 24- outlined inFig. l and illustrated in Fig. 3 are inserted into hollow interiorportions 80 and 82 of insulating housings 80' and 8-2. The insulatorboard 10 is now formed of a straight piece 90 of insulating materialonto which a conducting material generally indicated by numeral 20' isbonded or suitably secured providing end contacting portions 92 and 94which are connected by a bridge portion 96 formed of a predeterminedshape and thickness to provide proper fuse rating for a printed circuittype fuse in accordance with the present invention. The straight type ofprinted circuit protective device illustrated in Fig. 4 can be used inelectrical circuits where no fuse block or terminal board is providedsuch as in a power supply line to an electrical device. An example ofsuch a use would be in an automotive radio (not shown) where a fuseoften is inserted in series with a power supply line and where ends ofwires can be provided with terminals, such as the terminals 24 shown inthe drawings, permitting telescoping engagement of the insulatinghousing'members 80 and 82 completely enclosing the straight printedcircuit type fuse having the insulating board 90 and conducting material20. Thus the printed circuit ty'pe fuse is enclosed by a shieldingportion 98 of the one housing 80'. Ends 92 and 94 of conducting materialof the printed circuit type fuse are in good electrical engagement withbent over wing portions of terminals as described with Fig. 1 above.

It is readily seen that the printed circuit type fuse in accordance withthe present invention provides the advantages of simple construction dueto elimination of glass tube for housing fuses such as were previouslyknown in the art. Also eliminated are mica windows and other housingconstructions formed integral with the fuse for protective purposes. Theprinted circuit type fuse disclosed in the present invention needs nointegral housing because the printed circuit structure is adapted to beweatherproof when made in accordance with printed circuit methods ofmanufacture known in the art of printed circuits. The printed circuittype fuse using the conducting material 20 and insulating board 10 willnot deteriorate due to weather and electrical shielding is provided.with the fuse block as shown in Fig. 3 by lateral and longitudinalspacing of the U-shaped fuse device. Electrical shielding can also beprovided by the housing 82' insertable into the shielding portion end(98) of a housing 80' for enclosing terminals such as 24 as well as thestraight type printed circuit fuse in the present invention.Conceivably, a plurality of insulating housings 80' and 82' can beprovided adjacent to each other or as in integral longitudinal row ofterminal receiving insulating housings. Molded plastic fuse blocks areinexpensive to produce and the printed circuit type electrical fuse iseasy to connect between electrical terminals to provide protection foroverload and short circuit currents which may be encountered inelectrical circuits. Savings in fuses and in materials are appreciableand the simplicity as disclosed in the present invention is especiallyadvantageous for use with electrical circuits on automotive vehicleswhere multiple circuit fuse protection is provided and where fuses mustbe readily accessible without excessive cost in the fuse itself andcomponents for connecting the fuse in an electric circuit.

While the embodiments of the present invention as herein disclosedconstitute a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. Fuse and fuse mounting means, comprising, an insulating housing meansproviding a plurality of cavities spaced laterally and longitudinally ofeach other, terminal means mounted in the cavities and having aconductor receiving portion and an integral platform portion withlaterally bent-over side wings, and a printed circuit type fuseincluding a substantially U-shaped insulator board and only one printedcircuit conducting material covering part of one side of said board suchthat opposite ends of the U-shaped board are slidably engageable withsaid platform portion and side wings to effect electrical connectiondirectly with said one printed circuit conducting material; adapted toresult in disintegration of a bridge of said same printed circuitconducting material between said terminal means upon excess heatingbyoverload current.

2. A printed circuit type fuse and fuse block assembly, comprising, afuse block of insulating material having a plurality of openingstherein, female terminal means connected directly to conductors andhaving integral platform portions with bent-over side wings insertablein the openings, a plurality of printed circuit type fuses eachincluding a substantially U-shaped insulator board having leg portionsintegral with a bridge portion, said printed circuit type fuses alsoeach including only one conducting material covering one side of each ofsaid leg portions and extending integrally therebetween over a part ofsaid bridge portion, said bridge portion including an integral extensionfor handling said printed circui type fuse, said platform portions withbent-over side wings engaging directly the printed circuit conductingmaterial on said leg portions inserted relative to only said femaleterminal means in pairs of openings of said fuse block, said extensionsfor handing each of said fuses extending in a stacked array parallel toeach other with outer edges of said insulator board around eachextension being spaced from the conducting material bridge as protectionagainst electrical shorting and breaking of said printed circuitconducting material due to anything other than electrical overload inthe material itself.

3. Fuse and fuse mounting means, comprising, an in sulating bodyproviding at least a pair of cavities spaced laterally andlongitudinally of each other, female terminal means mounted in thecavities and having a conductor receiving portion and an integralplatform portion with laterally bent-over side wings, and a printedcircuit type fuse including only a substantially U-shaped insulatorboard and only one printed circuit conducting material covering part ofone side of said board such that opposite ends of the U-shaped board areslidably and directly engageable with said platform portion and sidewings to effect electrical connection directly with said one printedcircuit conducting material adapted to result in disintegration of abridge of said same printed circuit conducting material between saidterminal means upon excess heating by overload current, said U-shapedinsulation board at each of said opposite ends having a bevelled portionadapted to engage said platform portion of said female terminal meansfor guiding said ends relative to said one printed circuit conductingmaterial so that said side wing portions of said female terminal meanswill not damage and tear away said conducting portion.

4. The fuse and fuse mounting means of claim 3 wherein said insulatorboard includes an integral handle portion intermediatae said oppositeends, said handle portion having a cutout therein adapted to be engagedfor pulling said opposite ends of said insulator board and conductingmaterial out of direct electrical connection with said platform portionand side wings of said female terminal means.

References Cited in the file of this patent UNITED STATES PATENTS (Otherreferences on following page) UNITED STATES PATENTS I Barklie Oct. 4,1927 Vail Apr. 26,1949 Heath -Jan. 9,1951 Sundt May 18, 1954 Matthysee Ju1y 6, 1954 8 Sundt Nov. 6, 1956 Pempey Mar. 19, 1957 FOREIGN PATENTSGreat Britain Jan. 26, 1939 France Nov. 6, 1944

